Retrospective analysis of L5–S1 axial lumbar interbody fusion (AxiaLIF): a comparison with and without the use of recombinant human bone morphogenetic protein-2

Abstract

Since approval by the Food and Drug Administration in 2002, use of recombinant human bone morphogenetic protein-2 (rhBMP-2) to promote spinal fusion is increasing. In this comparative analysis, the authors assess fusion rates and clinical outcomes of patients who underwent a presacral axial lumbar interbody fusion (AxiaLIF) (TranS1 Inc., Wilmington, NC, USA) at L5-S1 with posterior instrumentation, with or without rhBMP-2. Retrospective case-matched chart review. A matched cohort of 99 patients underwent fusion performed by two surgeons at two institutions (2005-2007): Specifically, 45 patients at The Christ Hospital received rhBMP-2 and 54 patients at the University of Pittsburgh had no rhBMP-2. Pre- and postoperative visual analog scale (VAS) scores were recorded, as was physiologic data on fusion rates, blood loss, and length of stay. Preoperative and postoperative Oswestry Disability Index (ODI) scores were obtained for patients treated with rhBMP-2. Odom's outcome criteria were obtained at 2-year follow-up for patients without rhBMP-2. Data were collected prospectively. Demographic data, including sex and age, were matched. During the 2-year follow-up period, patients noted reduction in back pain and improved functional outcome measures. The most rapid reduction in VAS pain scores and improvement in ODI occurred within the first 3 months after surgery. Mean pre- and postoperative VAS scores improved 59% from 72.9 to 30.1 with rhBMP-2 and 72% from 81.3 to 22.6 without rhBMP-2. In rhBMP-2-treated patients, mean ODI scores were 54.4% preoperatively and 23.7% postoperatively, a 56.4% improvement at 2 years. In the non-rhBMP-2 patients, 80% reported excellent to good results using Odom criteria. Fusion rates were 96% with rhBMP-2 and 93% without rhBMP-2. Operative blood loss averaged 82 cm(3) with and less than 50 cm(3) without rhBMP-2. No differences in hospital length of stay were noted between the two groups or in the fusion rates with pedicle screws or facet screws. No major complications occurred with or without rhBMP-2. In our case-matched series, clinical outcomes were similar for patients who underwent an AxiaLIF L5-S1 interbody fusion with or without rhBMP-2. The data strongly suggest that there is a high confidence for no effect on fusion rate by using rhBMP-2.